v3.26.3
Pensions and other post-retirement benefit obligations - Schedule of key actuarial assumptions (Details)
Sep. 30, 2026
Mar. 31, 2026
UK    
Disclosure of defined benefit plans [line items]    
Discount rate 6.45% 6.00%
Rate of increase in RPI – UK 3.05% 3.17%
US    
Disclosure of defined benefit plans [line items]    
Discount rate 6.40% 5.60%